The convenience and reliability they offer.
I just make a phone call when I need a propane delivery and they come and refill the tank, afterwards they send the bill to my address. Very convenient.
Promptness of a return phone call from my local provider and Mike Gwaltney, driver, does a great job getting the gas hose to the tank and not damaging any plants and shrubs that are close by. Everyone has always provided 1st Class service.